<!DOCTYPE html>
<html lang="en">
<head>
    <title>Document</title>
    <style>
        div {
            margin: 10px auto;
            width: 400px;
            height: 400px;
            border-radius: 50%;
            background-color: #ccc;
        }
        .display {
            background-color: coral;
        }
    </style>
</head>
<body>
    <div>
    </div>
    <script>
        var divEle = document.querySelector("div");
        document.onclick = function () {
            divEle.classList.toggle("display");
        }
    </script>
</body>
</html>